1. Field of the Invention
The present invention relates to a damping force control apparatus for a vehicle equipped with adjustable-damping-force shock absorbers.
2. Description of the Related Art
Japanese Patent No. 3509544 discloses such a damping force control apparatus for a vehicle. In the disclosed damping force control apparatus, four wheels are suspended on the vehicle body via suspension systems including respective shock absorbers, and the damping forces of the shock absorbers are controlled individually in accordance with the turning conditions of the vehicle. In the damping force control apparatus, a virtual vehicle model in which a shock absorber for suppressing rising of the vehicle body and a shock absorber for suppressing rolling of the vehicle body are disposed at a virtual point on the radially inner side of a turning locus is adapted to an actual vehicle model.
In the damping force control apparatus disclosed in the patent, when the vehicle turns, the damping forces of the shock absorbers for the wheels on the radially inner side of a turning locus are set higher than those of the shock absorbers for the wheels on the radially outer side of the turning locus in order to suppress the rolling of the vehicle body while suppressing rising of the vehicle body at the wheels on the radially inner side of the turning locus. Thus, rising of the center of gravity of the vehicle during turning is suppressed, whereby rolling of the vehicle body can be suppressed, and steerability during turning can be improved.
However, the damping force control apparatus disclosed in the patent does not take into consideration the phase difference (time difference) between a lateral acceleration acting on the vehicle and a corresponding change in the posture of the vehicle body; for example, rolling of the vehicle body. Therefore, in some cases, after generation of a lateral acceleration, the posture of the vehicle body changes with a considerable time lag. In such a case, satisfactory riding comfort cannot be ensured during turning.